The present disclosure relates to a unit attachment-detachment mechanism including a unit attachable to and detachable from an apparatus main body and a pair of guide rails slidably supporting the unit, and also relates to an image forming apparatus incorporating such a unit attachment-detachment mechanism.
Conventionally, in an image forming apparatus relying on an electrophotographic process, a fixing unit, a drum unit, a developing unit, an intermediary transfer unit, and the like are fixed with screws in predetermined positions inside the image forming apparatus. On the other hand, when a sheet that has stuck (a jam) is dealt with, those units need to be taken out of the main body of the image forming apparatus. Also, if any unit has a service life shorter than that of the image forming apparatus, it needs to be replaced regularly.
With the conventional configuration mentioned above, every time a unit needs to replaced or a stuck sheet (a jam) needs to be dealt with, a serviceperson has to be sent for, resulting in low efficiency. On the other hand, for a non-professional user, attaching or detaching a unit using tools is a great burden. Against this background, there have been proposed methods that allow a user easy replacement of units, and according to a widely adopted configuration, a unit is inserted and pulled out along a guide shape provided in the main body of an image forming apparatus.
For example, in one known image forming apparatus, there are provided an intermediary transfer unit and a pair of guide rails that slidably supports engagement projections on side faces of the intermediary transfer unit. The intermediary transfer unit, when attached to the apparatus main body, has to be in contact with a drum unit but, in the middle of being attached or detached, has to be out of contact with the drum unit, a developing unit, and the like. Thus, to permit the intermediary transfer unit to move in the up-down direction (in the direction away from the drum unit), the guide rails have inclined portions.